2011年6月10日 星期五

液態氮做漢堡(不是麻油雞冰淇淋啦)

前幾天看的，滿有意思，而且感覺會work，有空再來翻。
June 6, 2011
Could Liquid Nitrogen Help Build Tasty Burgers?
By JOHN TIERNEY

The World Science Festival this past week was another triumph of cultural cross-pollination, but I’m afraid there was one missed opportunity to bring art and science together. If only someone had thought to put Daniel Boulud and Nathan Myhrvold on the same stage, we could have considered the ultimate interdisciplinary question: Can science create a better burger?

While scientists were convening at festival events all over New York City, Mr. Boulud, the famed French chef, and fellow foodies were participating in a separate symposium on Friday with a wonderfully grandiose title, “The State of the Hamburger.” The symposium, sponsored by Esquire magazine, was held to commemorate the 10th anniversary of the introduction of Mr. Boulud’s hamburger, which the food experts dated as the beginning of the international burger renaissance.

That delicacy, oddly enough, was the indirect result of the anti-burger movement a decade ago in France, where protesters became national heroes by ransacking a McDonald’s. During that controversy, when I asked French chefs in New York what they thought of hamburgers, Mr. Boulud called them the world’s most successful snack and said the French were just jealous.

“The French wish they could have invented McDonald’s,” he said, and added, as an afterthought, that he’d always wanted to invent an “adult burger” himself. Then he invited me and my wife to his kitchen to watch him create one combining Wyoming beef, black truffles and Colorado short ribs braised in red wine.

“I’ll call it the D B Burger,” Mr. Boulud told me as we scarfed the first ones in his kitchen. “Maybe we’ll open a drive-in window and sell it in a bag.” He was kidding about the bag but not, as it turned out, about the burger, which has become the $32 signature dish of his DB bistros and inspired haute-priced rivals around the world.

So far, though, restaurant chefs haven’t embraced the scientific techniques developed by Dr. Myhrvold. He is the former chief technology officer for Microsoft and the author, with a team of collaborators, of “Modernist Cuisine,” the new six-volume tome on technologically enhanced cooking. To build a better burger, he told me, you must understand its fundamental appeal.

“First, you have to consider the basic physics of sandwiches,” Dr. Myhrvold said. “When you bite down into it and pull it away from your mouth, you can’t have the center pull out from the sandwich. The meat has to be really tender. You’ve got to do violence to it, either by slicing it really thin, like a roast beef sandwich, or grinding it to make a sausage.”

The hamburger makes an ideal sausage, he said, because the meat flavor isn’t diluted by the curing salts used in hot dogs, and beef is more tender than pork because it has lower levels of myosin, the protein found in muscles. But there’s still enough myosin so that when the proteins are heated, they bond to create a gel that holds the patty together without the need for a casing.

The result is a cooked meat that’s less rubbery than other sausages and has a fresh-cooked taste that can’t be matched by cold cuts or reheated meats. It succulently exploits the Maillard reaction, named after a 20th-century Frenchman who explained the chemistry of browning meat and other foods.

When the beef patty hits the hot grill, the water at the lower surface quickly boils away, producing a very thin, dry crust, actually a transparent gel, called the desiccation zone. Immediately above is the Maillard zone, where heat causes reactions among sugars and proteins that turn the meat brown, yielding molecules with an intrinsically appealing flavor — at least to most humans.

“Most animals are afraid of fire, but we love to stare into it and smell cooking meat,” Dr. Myhrvold said. “The Maillard reactions are especially intense in hamburgers because a flat patty has a high ratio of surface area to volume.”

Our affection for those Maillard flavors near the surface may be a cultural heritage from our cattle-herding ancestors, and also perhaps an inheritance from hunter-gatherers. The anthropologist Richard Wrangham has hypothesized that cooking was essential to the brain’s evolution, because cooked food required less energy to digest, thereby providing our ancestors with a fuel-efficient way to power a large brain.

The burger’s immediate evolutionary antecedents were the 18th-century “Hamburg steaks” of the German port city whose name was applied to various ground-beef sandwiches sold in the United States at restaurants and fairs in the 19th century. Although these sandwiches were called hamburgers, they didn’t have all the quintessential elements, according to Josh Ozersky, the author of “The Hamburger: A History.”

He credits Walter Anderson with creating the hamburger at a restaurant in Wichita, Kan., in 1916, which turned into the first White Castle eatery five years later. Mr. Anderson’s crucial innovations were to use a specialized bun (instead of bread slices), to cook the meat on a very hot grill (500 degrees Fahrenheit), and to press down on the patty with a customized spatula made of high-strength steel.

Those breakthroughs assured global domination, in Mr. Ozersky’s view. “There is an inevitability to the hamburger,” he said. “It is the most concentrated and convenient way a person can cheaply eat everything that people like about beef.” Dr. Myhrvold agrees that the technological breakthroughs at White Castle were crucial.

“Pressing down with the spatula counteracts the tendency of the burger to lift off the grill due to the steam escaping from the bottom,” Dr. Myhrvold said. “When you press it against a very hot surface, you maximize the Maillard reaction. The great challenge in a burger is to create the Maillard flavors on the outside while keeping the inside fairly pink. Gray meat is tasteless and tough because you’ve broken down the proteins without breaking down the collagen.”

Dr. Myhrvold’s solution to this challenge is a twofold process developed by the “Modernist Cuisine” laboratory team. First, put the beef patty in a plastic bag and cook it sous vide — immersed in warm water for about half an hour until the core temperature reaches about 130 degrees. Next, dip the patty in liquid nitrogen for 30 seconds to freeze the outer millimeter of the meat, and then deep-fry in 450-degree oil for one minute.

“The freezing followed by the burst of high heat lets you brown the outside without overcooking the inside,” Dr. Myhrvold said. And the deep-frying is supposed to be a technological improvement over the classic White Castle spatula-on-a-griddle technique.

“On a griddle,” he explained, “even when you press a burger with a spatula, you can’t make all of it contact the surface because the edge of the burger is crenellated, with all these nooks and crannies formed by the cylinders of raw meat. But if you put it in hot fat, that fat penetrates and you get a super-thin layer of crispy Maillard browning all the way around those meat fibers.”

This laboratory innovation elicited a tactfully noncommittal response from Mr. Boulud on Friday at the “State of the Hamburger” symposium. “It’s very interesting, the nitrogen freezing,” the chef said, but he wondered if it would be either practical or tasty.

Well, that’s just the kind of experiment to try at the next World Science Festival: a cook-off between Mr. Boulud and Dr. Myhrvold. The DB Burger versus Nathan’s Nitrogen Burger. May the better Maillard win!